This invention relates to overload responsive circuit breakers which are mounted in a panelboard or load center for protecting apparatus in a branch distribution circuit. More particularly, this invention relates to circuit breakers of the aforementioned type wherein the electrical connection to the power supply of the panelboard or load center is effected by a bolt-in connection of the circuit breaker terminal to the supply bus of the panelboard or load center. Specifically, the invention is related to an improved retainer for captivating a threaded fastener element on the terminal of the circuit breaker while the circuit breaker is detached from the panelboard or load center.
It is desirable to retain the threaded fastener element of a bolt-in circuit breaker in operative position on the terminal of that device primarily for the convenience of the installer. With the fastener so retained, it will not become lost in shipping or handling of the circuit breaker. Also, the connection of the circuit breaker terminal to the panelboard or load center supply bus is located at the rear side of the breaker, substantially remote from the front surface thereof, and access to the fastener element is therefore restricted. By retaining the fastener element in operative position on the terminal, the installer can readily attach the circuit breaker to the panelboard or load center and complete the electrical connection thereof with a screwdriver or similar tool. In addition to the convenience factors, retainment of the fastener element on the circuit breaker terminal affords a safety advantage. The installer is not required to reach into a hard to access location to hold a loose fastener while attempting to engage that fastener with a tool, thereby potentially dropping the fastener to fall to an undetermined position within the panelboard apparatus wherein it could significantly reduce opposite polarity electrical spacings of that apparatus if not retrieved before power is again applied to the panelboard.
An example of bolt-in circuit breakers mounted within a panelboard is shown in U.S. Pat. No. 4,358,815 issued Nov. 9, 1982 to H. E. Koslosky et al and assigned to the assignee of this application. In that patent, a cylindrically shaped, internally threaded nut is shown retained in position on the terminal of a circuit breaker by a nylon retainer having a loop surrounding the body of the nut and a tongue tucked under an insulating sleeve which is shrink-fit over a leg of the circuit breaker terminal. Although the retainer described therein is well suited for its intended purpose, the assembly method is expensive and is not well suited for automated circuit breaker assembly. Other retainers have been attempted for use in an automated assembly circuit breaker, but for one reason or another were found to be less than well suited for the intended purpose. For example, in one embodiment a wire loop was placed around the body of the fastener, and the ends of the wire loop were brought closely together, then formed to extend parallel, substantially radially from the loop through an opening in the terminal. The distal ends of the wires were formed over to engage the rear side of the terminal to prevent withdrawal through the opening. However, this structure did not positively locate the fastener in the proper orientation on the terminal for testing purposes during assembly and did not adequately position the fastener in an operative position for installation. Another version provided a cage on the terminal member loosely captivating the threaded fastener therein, but this version added cost and significantly increased the width of the terminal assembly.